Question 1

Which of the following statements best explains why unsaturated fatty acids have lower melting points than saturated fatty acids?

Accepted Answer

Unsaturated fatty acids have cis double bonds that create kinks, preventing tight packing and reducing dispersion forces.

Question 2

A patient is diagnosed with a genetic disease caused by a single base mutation in a gene. Which of the following best describes how this mutation can lead to disease?

Accepted Answer

The mutation changes the DNA sequence, which can alter the mRNA codon and result in a protein with an incorrect amino acid sequence that does not function properly.

Question 3

Which of the following best describes the difference between amylose and cellulose?

Accepted Answer

Amylose has $$\alpha-$$glycosidic bonds and is digestible by humans, while cellulose has $$\beta-$$glycosidic bonds and is not digestible by humans.

Question 4

A triacylglycerol is hydrolyzed in the presence of a strong base such as NaOH. Which products are formed in this reaction?

Accepted Answer

Glycerol and the sodium salts of three fatty acids (soap)

Question 5

Which of the following best describes the structure of a steroid?

Accepted Answer

A molecule with four fused carbon rings

Question 6

Which of the following statements about protein structure is correct?

Accepted Answer

Tertiary structure is stabilized by interactions such as hydrogen bonds, disulfide bonds, hydrophobic interactions, and salt bridges between side chains.

Question 7

A sample of DNA has the following sequence on one strand: 5'-ATGCCGTA-3'. What is the sequence of the complementary DNA strand?

Accepted Answer

3'-TACGGCAT-5'

Question 8

Which of the following best explains why glycogen is a more efficient energy storage molecule in animals compared to amylose?

Accepted Answer

Glycogen is highly branched, providing more ends for rapid glucose release during metabolism.

Question 9

Which of the following is true regarding the hydrogenation of vegetable oils?

Accepted Answer

Hydrogenation converts some cis double bonds to single bonds, increasing the melting point and producing semi-solid fats.

Question 10

Which of the following best describes the role of mRNA in protein synthesis?

Accepted Answer

mRNA carries the genetic code from DNA in the nucleus to the ribosome for translation.

Question 11

A protein is exposed to high heat and extreme pH. Which of the following is most likely to occur?

Accepted Answer

The protein will denature, losing its secondary, tertiary, and quaternary structure.

Question 12

Which of the following best describes the difference between DNA and RNA?

Accepted Answer

DNA contains deoxyribose and the base thymine, while RNA contains ribose and the base uracil.

Question 13

Which of the following best describes the function of an enzyme inhibitor?

Accepted Answer

It binds to the active site or another site on the enzyme, preventing substrate binding or product formation.

Question 14

Which of the following is a correct statement about the structure of a nucleotide?

Accepted Answer

A nucleotide consists of a pentose sugar, a phosphate group, and a nitrogenous base.

Question 15

Which of the following best explains why humans cannot digest cellulose?

Accepted Answer

Humans lack the enzyme to hydrolyze $$\beta-$$glycosidic bonds present in cellulose.

Question 16

A polypeptide is synthesized with the following sequence: Gly-Ala-Ser. Which end of the polypeptide contains the free $$-\mathrm{NH}_3^+$$ group?

Accepted Answer

The N-terminus (left end) contains the free $$-\mathrm{NH}_3^+$$ group.

Question 17

Which of the following best describes the role of lipoproteins in the body?

Accepted Answer

Lipoproteins transport cholesterol and other nonpolar biomolecules through the bloodstream.

Question 18

Which of the following best describes the process of transcription in protein synthesis?

Accepted Answer

Transcription is the synthesis of mRNA from a DNA template in the nucleus.

Question 19

A fatty acid is described as 18:2 $$\omega-6. $$Which of the following correctly describes this fatty acid?

Accepted Answer

It has 18 carbon atoms, 2 double bonds, and the first double bond is at the 6th carbon from the methyl end.

Question 20

Which of the following best describes the effect of a noncompetitive inhibitor on enzyme activity?

Accepted Answer

It binds to a site other than the active site, changing the enzyme's shape and reducing its activity.

Biochemistry Fundamentals: Carbohydrates, Lipids, Proteins, and Nucleic Acids

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